This invention relates to a regulated power supply for a television receiver.
Television receivers, which obtain operating power from an alternating current source producing any one of a plurality of RMS potentials within a predetermined range, have, traditionally, been provided with various regulation circuits in order to maintain relatively uniform performance of the television receiver within the predetermined range of RMS potentials.
Many different types of regulation circuits have been used. One type controls various critical direct current potentials while not controlling some less critical direct current potentials in the television receiver. Another type provides for compensation in each of the individual circuits of the television receiver for variations in direct current potentials. A third type controls the entire source of direct current potentials for the television receiver.
One regulator circuit for controlling the entire source of direct current potentials rectifies the first alternating current potential to produce a first direct current potential, chops the first direct current potential by means of an oscillator to produce a second alternating current potential, transforms the second alternating current potential to one or more levels and rectifies the transformed alternating current potentials to produce the desired direct current operating potentials. The regulation is accomplished by sampling one of the operating potentials and controlling the duty cycle of the oscillator to maintain the sampled operating potential at a relatively stable level. This circuit, while providing an efficient means of regulating, does not provide for good regulation of more than the direct current operating potential being sampled when the load on non-sampled operating potentials is changed.
Another regulation circuit for controlling the entire source of direct current potentials rectifies the first alternating current potential to produce a first direct current potential and regulates the first direct current potential by a comparison to a reference source. To provide a number of direct current operating potential levels with high efficiency, the first direct current potential is chopped by means of an oscillator, transformed and rectified. This type of circuit provides good regulation of all operating direct current potentials within the range of RMS potentials as well as isolation between the source of alternating current and the television receiver chassis. However, this circuit is less efficient than the previously described circuit because of the power loss in the regulation of the first direct current potentials.
It would be desirable to accomplish the regulation afforded by the latter circuit with more efficiency and fewer components.